U.S. patent application number 15/314334 was filed with the patent office on 2017-07-06 for apparatus for assessing degradation and estimating strength by using ultrasound and method for assessing degradation and estimating strength using the same.
The applicant listed for this patent is INDUSTRY-UNIVERSITY COOPERATION FOUNDATION OF HANYANG UNIVERSITY. Invention is credited to Kyung Young JHANG, Jong Beom KIM.
Application Number | 20170191967 15/314334 |
Document ID | / |
Family ID | 54699176 |
Filed Date | 2017-07-06 |
United States Patent
Application |
20170191967 |
Kind Code |
A1 |
JHANG; Kyung Young ; et
al. |
July 6, 2017 |
APPARATUS FOR ASSESSING DEGRADATION AND ESTIMATING STRENGTH BY
USING ULTRASOUND AND METHOD FOR ASSESSING DEGRADATION AND
ESTIMATING STRENGTH USING THE SAME
Abstract
Provided is an apparatus for assessing degradation and
estimating strength by using ultrasound, in which the apparatus
includes: an ultrasound transmitting unit making an ultrasound
signal having a single frequency be incident in an inspected
object; an ultrasound receiving unit receiving the ultrasound
signal penetrating the inspected object or reflected on the
inspected object; a signal processing unit calculating a
propagation speed through a time interval of the ultrasound signal
received by the ultrasound receiving unit and separates the
received ultrasound signal into a fundamental frequency component
and a harmonic component to calculate non-linear parameter, and
measuring linear and non-linear elastic coefficients by using the
propagation speed and the non-linear parameter; and a strength
estimating unit obtaining a tensile curve by using the linear and
non-linear elastic coefficients and estimating at least one of
tensile strength and yield strength by using the tensile curve.
Inventors: |
JHANG; Kyung Young; (Seoul,
KR) ; KIM; Jong Beom; (Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
INDUSTRY-UNIVERSITY COOPERATION FOUNDATION OF HANYANG
UNIVERSITY |
Seoul |
|
KR |
|
|
Family ID: |
54699176 |
Appl. No.: |
15/314334 |
Filed: |
April 30, 2015 |
PCT Filed: |
April 30, 2015 |
PCT NO: |
PCT/KR2015/004443 |
371 Date: |
November 28, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N 29/12 20130101;
G01H 17/00 20130101; G01N 29/348 20130101; G01N 2291/02827
20130101; G01N 2291/044 20130101; G01N 29/36 20130101; G01N 29/07
20130101; G01N 2291/0258 20130101; G01N 29/24 20130101; G01N 29/46
20130101; G01N 29/44 20130101; G01N 2291/02491 20130101; G01N
29/4472 20130101 |
International
Class: |
G01N 29/12 20060101
G01N029/12; G01N 29/24 20060101 G01N029/24; G01H 17/00 20060101
G01H017/00; G01N 29/44 20060101 G01N029/44; G01N 29/36 20060101
G01N029/36 |
Foreign Application Data
Date |
Code |
Application Number |
May 28, 2014 |
KR |
10-2014-0064301 |
Sep 15, 2014 |
KR |
10-2014-0122307 |
Dec 11, 2014 |
KR |
10-2014-0178752 |
Apr 15, 2015 |
KR |
10-2015-0053382 |
Claims
1. An apparatus for assessing degradation and estimating strength
by using ultrasound, the apparatus comprising: an ultrasound
transmitting unit making an ultrasound signal having a single
frequency be incident in an inspected object; an ultrasound
receiving unit receiving the ultrasound signal penetrating the
inspected object or reflected on the inspected object; a signal
processing unit calculating a propagation speed through a time
interval of the ultrasound signal received by the ultrasound
receiving unit and separates the received ultrasound signal into a
fundamental frequency component and a harmonic component to
calculate non-linear parameter, and measuring linear and non-linear
elastic coefficients by using the propagation speed and the
non-linear parameter; and a strength estimating unit obtaining a
tensile curve by using the linear and non-linear elastic
coefficients and estimating at least one of tensile strength and
yield strength by using the tensile curve.
2. The apparatus of claim 1, wherein the signal processing unit
measures a 2nd order non-linear parameter, a 3rd order non-linear
parameter, and a linear elastic coefficient by controlling the
ultrasound transmitting unit and the ultrasound receiving unit and
measure a 2nd order non-linear elastic coefficient and a 3rd order
non-linear elastic coefficient by using the 2nd order non-linear
parameter, the 3rd order non-linear parameter, and the linear
elastic coefficient, and the strength estimating unit obtains the
tensile curve by using the linear elastic coefficient, the 2nd
order non-linear elastic coefficient, and the 3rd order non-linear
elastic coefficient or obtains the tensile curve by using the
linear elastic coefficient, the 2nd order non-linear parameter, and
the 3rd order non-linear parameter.
3. The apparatus of claim 1, wherein the signal processing unit
estimates an absolute non-linear parameter of the inspected object
by using a ratio of relative non-linear parameters of a reference
sample and the inspected object and the absolute non-linear
parameter of the reference sample and measures the linear and
non-linear elastic coefficients by using the propagation speed and
the absolute non-linear parameter.
4. The apparatus of claim 3, wherein the ratio of the relative
non-linear parameter is calculated through an operation of dividing
the relative non-linear parameter of the inspected object by the
relative non-linear parameter of the reference sample.
5. The apparatus of claim 1, wherein the strength estimating unit
estimates the tensile strength from a maximum value of the tensile
curve.
6. The apparatus of claim 1, wherein the strength estimating unit
estimates the yield strength by applying 0.2% offset to the tensile
curve.
7. The apparatus of claim 1, further comprising: a degradation
assessing unit assessing a damage time of the inspected object
based on an accumulated non-linear parameter calculated by
accumulating a variation amount of the non-linear parameter.
8. The apparatus of claim 7, wherein the signal processing unit
obtains the non-linear parameter of the ultrasound signal received
by the ultrasound receiving unit depending on the time and
accumulates the variation amount of the non-linear parameter to
calculate the accumulated non-linear parameter.
9. An apparatus for assessing degradation and estimating strength
by using ultrasound, the apparatus comprising: an ultrasound
transmitting unit making an ultrasound signal having a single
frequency be incident in an inspected object; an ultrasound
receiving unit receiving the ultrasound signal penetrating the
inspected object or reflected on the inspected object; a signal
processing unit obtaining the non-linear parameter of the
ultrasound signal received by the ultrasound receiving unit
depending on the time and accumulating the variation amount of the
non-linear parameter to calculate the accumulated non-linear
parameter; and a degradation assessing unit assessing a damage time
of the inspected object based on the accumulated non-linear
parameters.
10. A method for assessing degradation and estimating strength by
using ultrasound, the method comprising: making an ultrasound
signal having a single frequency be incident in an inspected
object; receiving the ultrasound signal penetrating the inspected
object or reflected on the inspected object; calculating a
propagation speed through a time interval of the received
ultrasound signal; separating the received ultrasound signal into a
fundamental frequency component and a harmonic component to
calculate non-linear parameter; measuring linear and non-linear
elastic coefficients by using the propagation speed and the
non-linear parameter; obtaining a tensile curve by using the linear
and non-linear elastic coefficients; and estimating at least one of
tensile strength and yield strength by using the tensile curve.
11. The method of claim 10, wherein the calculating of the
non-linear parameter includes separating the received ultrasound
signal into a fundamental frequency component and a harmonic
component to calculate a 2nd order non-linear parameter and a 3rd
order non-linear parameter, the measuring of the linear and
non-linear elastic coefficients includes, measuring a linear
elastic coefficient based on the propagation speed, and measuring a
2nd order non-linear elastic coefficient and a 3rd order non-linear
elastic coefficient by using the 2nd order non-linear parameter,
the 3rd order non-linear parameter, and the linear elastic
coefficient, and the obtaining of the tensile curve includes,
obtaining the tensile curve by using the linear elastic
coefficient, the 2nd order non-linear elastic coefficient, and the
3rd order non-linear elastic coefficient, and obtaining the tensile
curve by using the linear elastic coefficient, the 2nd order
non-linear parameter, and the 3rd order non-linear parameter.
12. The method of claim 10, wherein the measuring of the linear and
non-linear elastic coefficients includes, estimating an absolute
non-linear parameter of the inspected object by using a ratio of
relative non-linear parameters of a reference sample and the
inspected object and the absolute non-linear parameter of the
reference sample, and measuring the linear and non-linear elastic
coefficients by using the propagation speed and the absolute
non-linear parameter.
13. The method of claim 10, wherein the estimating includes
estimating the tensile strength from a maximum value of the tensile
curve.
14. The method of claim 10, wherein the estimating includes
estimating the yield strength by applying 0.2% offset to the
tensile curve.
15. The method of claim 10, further comprising: calculating
accumulated non-linear parameters by accumulating a variation
amount of the non-linear parameter; and assessing a damage time of
the inspected object based on the accumulated non-linear
parameters.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to an apparatus for assessing
degradation and estimating strength by using ultrasound and a
method for assessing degradation and estimating strength using the
same.
BACKGROUND ART
[0002] In recent years, a research into an assessment apparatus
which calculates an ultrasonic non-linear parameter by using the
amplitude of a fundamental frequency and the amplitude of a
harmonic frequency of ultrasound penetrating an inspected object by
making the ultrasound be incident in the inspected object and
assesses a change in physical property of the inspected object by
using the calculated ultrasonic non-linear parameter has been in
active progress.
[0003] However, when the inspected object is heat-treated and the
inspected object is thus degraded, precipitates are generated and
thereafter, the precipitates are grown and coupled, and dissoluted
and the ultrasonic non-linear parameter also increases and
decreases according to the nucleation and growth of the
precipitates.
[0004] Accordingly, it is difficult to measure clearly and
accurately a degradation degree of the inspected object by using
the assessment apparatus in the related art. That is, when the
inspected object is degraded, the ultrasonic non-linear parameter
also increases and decreases as the quantity of precipitates
increases and decreases and since the assessment apparatuses in the
related art can measure the degradation degree of the inspected
object based on only the ultrasonic non-linear parameter at a
specific time, the degradation degree may be ambiguous and
inaccurate.
[0005] Meanwhile, a propagation speed of an elastic wave in a solid
is determined by physical properties such as an elastic
coefficient, a density, and a Poisson's ratio of a propagation
medium. Accordingly, the elastic coefficient of the propagation
medium is acquired by measuring the propagation speed of the
elastic wave to estimate the physical properties of the propagation
medium. A method for acquiring the elastic coefficient of the
propagation medium includes a linear elastic coefficient measuring
method that measures the propagation speed of the ultrasound by
using the ultrasound which belongs to the elastic wave to calculate
a liner elastic coefficient.
[0006] However, there is a disadvantage in that a minute change and
degradation of a micro characteristic or an elastic property of the
propagation medium cannot be evaluated by the linear elastic
coefficient measuring method. As a method for remedying such a
disadvantage, a theoretical research into a correlation between the
ultrasonic non-linear parameter and the non-linear elastic
coefficient is performed.
[0007] As a result of the research, a relationship between a 2nd
order ultrasonic non-linear parameter and a 2nd order non-linear
elastic coefficient is verified. As described above, the
correlation between the 2nd order ultrasonic non-linear parameter
and the 2nd order non-linear elastic coefficient is researched, but
a research into 3rd or high order ultrasonic non-linear parameters
and 3rd or high order non-linear elastic coefficients is not
made.
[0008] As associated prior art, Korean Patent Laid-open Publication
No. 10-2012-0031674 (Title of Disclosure: System and Apparatus for
Measuring Non-linearity of Ultrasonic Wave, Apr. 4, 2012) is
provided.
DISCLOSURE
Technical Problem
[0009] An object to be achieved by the present disclosure is to
provide an apparatus for assessing degradation and estimating
strength by using ultrasound, and a method for assessing
degradation and estimating strength using the same which can
quantitatively assess degradation of an inspected object by using
the ultrasound and estimate the strength of the inspected object by
a non-destruction method.
[0010] The objects to be solved by the present disclosure are not
limited to the aforementioned object(s), and other object(s), which
are not mentioned above, will be apparent to a person having
ordinary skill in the art from the following description.
Technical Solution
[0011] According to another aspect of the present disclosure, there
is provided an apparatus for assessing degradation and estimating
strength by using ultrasound, including: an ultrasound transmitting
unit making an ultrasound signal having a single frequency be
incident in an inspected object; an ultrasound receiving unit
receiving the ultrasound signal penetrating the inspected object or
reflected on the inspected object; a signal processing unit
calculating a propagation speed through a time interval of the
ultrasound signal received by the ultrasound receiving unit and
separates the received ultrasound signal into a fundamental
frequency component and a harmonic component to calculate
non-linear parameter, and measuring linear and non-linear elastic
coefficients by using the propagation speed and the non-linear
parameter; and a strength estimating unit obtaining a tensile curve
by using the linear and non-linear elastic coefficients and
estimating at least one of tensile strength and yield strength by
using the tensile curve.
[0012] The signal processing unit may measure a 2nd order
non-linear parameter, a 3rd order non-linear parameter, and a
linear elastic coefficient by controlling the ultrasound
transmitting unit and the ultrasound receiving unit and measure a
2nd order non-linear elastic coefficient and a 3rd order non-linear
elastic coefficient by using the 2nd order 2nd order non-linear
parameter, the 3rd order non-linear parameter, and the linear
elastic coefficient, and the strength estimating unit may obtain
the tensile curve by using the linear elastic coefficient, the 2nd
order non-linear elastic coefficient, and the 3rd order non-linear
elastic coefficient or obtains the tensile curve by using the
linear elastic coefficient, the 2nd order non-linear parameter, and
the 3rd order non-linear parameter.
[0013] The signal processing unit may estimate an absolute
non-linear parameter of the inspected object by using a ratio of
relative non-linear parameters of a reference sample and the
inspected object and the absolute non-linear parameter of the
reference sample and measures the linear and non-linear elastic
coefficients of the inspected object by using the propagation speed
and the absolute non-linear parameter.
[0014] The ratio of the relative non-linear parameter may be
calculated through an operation of dividing the relative non-linear
parameter of the inspected object by the relative non-linear
parameter of the reference sample.
[0015] The strength estimating unit may estimate the tensile
strength from a maximum value of the tensile curve.
[0016] The strength estimating unit may estimate the yield strength
by applying 0.2% offset to the tensile curve.
[0017] The apparatus may further include a degradation assessing
unit assessing a damage time of the inspected object based on an
accumulated non-linear parameter calculated by accumulating a
variation amount of the non-linear parameter.
[0018] The signal processing unit may obtain the non-linear
parameter of the ultrasound signal received by the ultrasound
receiving unit depending on the time and accumulates the variation
amount of the non-linear parameter to calculate the accumulated
non-linear parameter.
[0019] According to another aspect of the present disclosure, there
is provided an apparatus for assessing degradation and estimating
strength by using ultrasound, including: an ultrasound transmitting
unit making an ultrasound signal having a single frequency be
incident in an inspected object; an ultrasound receiving unit
receiving the ultrasound signal penetrating the inspected object or
reflected on the inspected object; a signal processing unit
obtaining the non-linear parameter of the ultrasound signal
received by the ultrasound receiving unit depending on the time and
accumulating the variation amount of the non-linear parameter to
calculate the accumulated non-linear parameter; and a degradation
assessing unit assessing a damage time of the inspected object
based on the accumulated non-linear parameters.
[0020] According to another aspect of the present disclosure, there
is provided a method for assessing degradation and estimating
strength by using ultrasound, including: making an ultrasound
signal having a single frequency be incident in an inspected
object; receiving the ultrasound signal penetrating the inspected
object or reflected on the inspected object; calculating a
propagation speed through a time interval of the received
ultrasound signal; separating the received ultrasound signal into a
fundamental frequency component and a harmonic component to
calculate non-linear parameter; measuring linear and non-linear
elastic coefficients by using the propagation speed and the
non-linear parameter; obtaining a tensile curve by using the linear
and non-linear elastic coefficients; and estimating at least one of
tensile strength and yield strength by using the tensile curve.
[0021] The calculating of the non-linear parameter may include
separating the received ultrasound signal into a fundamental
frequency component and a harmonic component to calculate a 2nd
order non-linear parameter and a 3rd order non-linear parameter,
the measuring of the linear and non-linear elastic coefficients may
include measuring a linear elastic coefficient based on the
propagation speed, and measuring a 2nd order non-linear elastic
coefficient and a 3rd order non-linear elastic coefficient by using
the 2nd order non-linear parameter, the 3rd order non-linear
parameter, and the linear elastic coefficient, and the obtaining of
the tensile curve may include obtaining the tensile curve by using
the linear elastic coefficient, the 2nd order non-linear elastic
coefficient, and the 3rd order non-linear elastic coefficient, and
obtaining the tensile curve by using the linear elastic
coefficient, the 2nd order non-linear parameter, and the 3rd order
non-linear parameter.
[0022] The measuring of the linear and non-linear elastic
coefficients may include estimating an absolute non-linear
parameter of the inspected object by using a ratio of relative
non-linear parameters of a reference sample and the inspected
object and the absolute non-linear parameter of the reference
sample, and measuring the linear and non-linear elastic
coefficients by using the propagation speed and the absolute
non-linear parameter.
[0023] The estimating may include estimating the tensile strength
from a maximum value of the tensile curve.
[0024] The estimating may include estimating the yield strength by
applying 0.2% offset to the tensile curve.
[0025] The method may further include calculating accumulated
non-linear parameters by accumulating a variation amount of the
non-linear parameter; and assessing a damage time of the inspected
object based on the accumulated non-linear parameters.
[0026] Detailed contents of other exemplary embodiments are
included in the detailed description and the accompanying
drawings.
Advantageous Effects
[0027] According to exemplary embodiments of the present
disclosure, tensile characteristics (tensile strength, yield
strength, and the like) of a material which can be acquired in a
destruction test such as a tensile test are assessed by using a
linear/non-linear elastic coefficient from ultrasound signals to
precisely diagnose degradation such as deterioration of a strength
characteristic and the strength of the material without performing
the tensile test.
[0028] According to the exemplary embodiments of the present
disclosure, when an apparatus for assessing degradation and
estimating strength by using ultrasound is installed in a structure
and used, the strength deterioration with time elapsed can be
continuously monitored, and as a result, the technique can be used
as a structural health monitoring (SHM) technique.
DESCRIPTION OF DRAWINGS
[0029] FIG. 1 is a block diagram illustrated for describing an
apparatus for assessing degradation and estimating strength by
using ultrasound according to an exemplary embodiment of the
present disclosure.
[0030] FIG. 2 is a graph illustrating an experimental result of
measuring a non-linear parameter depending on a heat treatment time
of an aluminum alloy in an exemplary embodiment of the present
disclosure.
[0031] FIG. 3 is a graph illustrating an experimental result of
measuring an accumulated non-linear parameter depending on a heat
treatment time of an aluminum alloy in an exemplary embodiment of
the present disclosure.
[0032] FIG. 4 is a diagram illustrated for describing one example
of estimating tensile strength, yield strength, and the like
through a tensile curve according to an exemplary embodiment of the
present disclosure.
[0033] FIGS. 5 to 7 are flowcharts illustrated for describing a
method for assessing degradation and estimating strength by using
ultrasound according to an exemplary embodiment of the present
disclosure.
[0034] FIG. 8 is a flowchart illustrated for describing a method
for assessing degradation and estimating strength by using
ultrasound according to another exemplary embodiment of the present
disclosure.
BEST MODE
[0035] Advantages and features of the present disclosure, and
methods for accomplishing the same will be more clearly understood
from exemplary embodiments described below with reference to the
accompanying drawings. However, the present disclosure is not
limited to the exemplary embodiments set forth below, and may be
embodied in various different forms. The present exemplary
embodiments are just for rendering the description of the present
disclosure complete and are set forth to provide a complete
understanding of the scope of the disclosure to a person with
ordinary skill in the technical field to which the present
disclosure pertains, and the present disclosure will only be
defined by the scope of the claims. Like reference numerals denote
like elements throughout the present specification.
[0036] Hereinafter, exemplary embodiments of the present disclosure
will be described in detail with reference to the accompanying
drawings.
[0037] FIG. 1 is a block diagram illustrated for describing an
apparatus for assessing degradation and estimating strength by
using ultrasound according to an exemplary embodiment of the
present disclosure.
[0038] Referring to FIG. 1, an apparatus 100 for assessing
degradation and estimating strength by using ultrasound according
to an exemplary embodiment of the present disclosure may include an
ultrasound transmitting unit 110, an ultrasound receiving unit 120,
a signal processing unit 130, a strength estimating unit 140, a
degradation assessing unit 150, and a control unit 160.
[0039] The ultrasound transmitting unit 110 makes an ultrasound
signal having a single frequency be incident in an inspected
object.
[0040] The ultrasound receiving unit 120 receives the ultrasound
signal penetrating the inspected object or reflected on the
inspected object.
[0041] Since the ultrasound transmitting unit 110 and the
ultrasound receiving unit 120 are generally known, description
thereof will be omitted.
[0042] The signal processing unit 130 calculates a propagation
speed through a time interval of the ultrasound signal received by
the ultrasound receiving unit 120 and separates the received
ultrasound signal into a fundamental frequency component and a
harmonic component.
[0043] The signal processing unit 130 acquires the amplitude of the
fundamental frequency component and the amplitude of the harmonic
component and substitutes the acquired amplitudes in Equation 1
given below to calculate a (2nd order) non-linear parameter.
.beta. = 8 A 2 A 1 2 k 2 x [ Equation 1 ] ##EQU00001##
[0044] Where, .beta. represents the (2nd order) non-linear
parameter, A.sub.1 represents an amplitude of the fundamental
frequency component and A.sub.2 represents the amplitude of the
harmonic component. Further, k represents a wave number and x
represents a propagation distance.
[0045] The signal processing unit 130 measures linear and
non-linear elastic coefficients by using the propagation speed and
the non-linear parameter.
[0046] In detail, the signal processing unit 130 may measure a 2nd
order non-linear parameter, a 3rd order non-linear parameter, and a
linear elastic coefficient by controlling the ultrasound
transmitting unit 110 and the ultrasound receiving unit 120 and
measure a 2nd order non-linear elastic coefficient and a 3rd order
non-linear elastic coefficient by using the 2nd order non-linear
parameter, the 3rd order non-linear parameter, and the linear
elastic coefficient.
[0047] The 2nd order non-linear parameter may be measured by
Equation 1 given above.
[0048] The 3rd order non-linear parameter may be measured by
Equation 2 given below.
[0049] That is, the signal processing unit 130 acquires the
amplitudes of the fundamental frequency component and a 3rd order
harmonic component separated from the ultrasound signal received by
the ultrasound receiving unit 120 and substitutes the acquired
amplitudes in Equation 2 given below to measure the 3rd order
non-linear parameter.
.gamma. = 32 A 3 A 1 3 k 4 x 2 [ Equation 2 ] ##EQU00002##
[0050] Herein, .gamma. represents the 3rd order non-linear
parameter, A.sub.1 represents the amplitude of the fundamental
frequency component, A.sub.3 represents the amplitude of the
harmonic component, k represents the wave number, and x represents
the propagation distance. The 3rd order non-linear parameter
satisfies a relationship of Equation 3 given below with the 2nd
order non-linear parameter.
.gamma.=.beta..sup.2 [Equation 3]
[0051] The linear elastic coefficient may be measured by Equation 4
given below.
[0052] That is, the signal processing unit 130 measures a
longitudinal wave propagation speed and a traverse wave propagation
speed of the ultrasound signal received by the ultrasound receiving
unit 120 and substitutes the propagation speeds in Equation 4 given
below to measure the linear elastic coefficient of the inspected
object.
E = .rho. ( 4 C s 4 - 3 C L 2 C S 2 2 C s 2 - 2 C L 2 ) [ Equation
4 ] ##EQU00003##
[0053] Where, E represents the linear elastic coefficient, .rho. a
density of a propagation medium, C.sub.L represents the traverse
wave propagation speed of the ultrasound, and C.sub.S represents
the longitudinal wave propagation speed.
[0054] The 2nd order non-linear elastic coefficient may be measured
by Equation 5 given below.
[0055] That is, the signal processing unit 130 substitutes the 2nd
order non-linear parameter and the linear elastic coefficient in
Equation 5 given below to measure the 3rd order non-linear elastic
coefficient.
F=.beta.E [Equation 5]
Where, F represents the 2nd order non-linear elastic coefficient,
.beta. represents the 2nd order non-linear parameter, and E
represents the linear elastic coefficient.
[0056] The 3rd order non-linear elastic coefficient may be measured
by Equation 6 given below.
[0057] A relationship between the 3rd order non-linear elastic
coefficient and the 3rd order non-linear parameter may be expressed
as the 3rd order non-linear elastic coefficient and the 2nd order
non-linear parameter as exhibited in Equation 6 given below.
[0058] Accordingly, the signal processing unit 130 substitutes the
linear elastic coefficient and the 2nd order non-linear parameter
in Equation 6 given below to measure the 3rd order non-linear
elastic coefficient.
G=1/2.gamma.E=1/2.beta..sup.2E [Equation 6]
[0059] Where, G represents the 3rd order non-linear elastic
coefficient and .gamma. represents the 3rd order non-linear
parameter. Further, E represents the linear elastic coefficient and
.beta. represents the 2nd order non-linear parameter.
[0060] Meanwhile, as another exemplary embodiment, the signal
processing unit 130 may estimate an absolute non-linear parameter
of the inspected object by using a ratio of relative non-linear
parameters of a reference sample and the inspected object and the
absolute non-linear parameter of the reference sample. The signal
processing unit 130 may measure the linear and non-linear elastic
coefficients by using the propagation speed and the absolute
non-linear parameter.
[0061] Herein, the ratio of the relative non-linear parameter of
the inspected object may be calculated through an operation of
dividing the relative non-linear parameter of the inspected object
by the relative non-linear parameter of the reference sample.
[0062] A process of estimating the absolute non-linear parameter of
the inspected object will be described below.
[0063] That is, the signal processing unit 130 separates the
received ultrasound signal into the fundamental frequency component
and a secondary harmonic component by using a band pass filter to
measure the relative non-linear parameters of the reference sample
and the inspected object. The signal processing unit 130 applies
the fundamental frequency component and the secondary harmonic
component to a non-linear parameter equation (Equation 7) given
below to measure the relative non-linear parameter values of the
reference sample and the inspected object.
.beta. ' = A 2 A 1 2 [ Equation 7 ] ##EQU00004##
[0064] Where, .beta.' represents the (2nd order) non-linear
parameter, A.sub.1 represents the amplitude of the fundamental
frequency component, and A.sub.2 represents the amplitude of the
2nd order harmonic component, respectively.
[0065] Next, the signal processing unit 130 may calculate the ratio
of the relative non-linear parameters of the reference sample and
the inspected object through an operation of dividing the relative
non-linear parameter by the relative non-linear parameter of the
reference sample as exhibited in Equation 8 given below.
r .beta. = .beta. ' .beta. 0 ' [ Equation 8 ] ##EQU00005##
[0066] Where, r.sub..beta. represents the ratio of the relative
non-linear parameter value, .beta..sub.0' represents the relative
non-linear parameter value of the reference sample, and .beta.'
represents the relative non-liner parameter value of the inspected
object.
[0067] Next, the signal processing unit 130 may estimate the
absolute non-linear parameter of the inspected object by using the
calculated ratio of the relative non-linear parameters and the
absolute non-linear parameter of the reference sample.
[0068] In this case, the signal processing unit 130 may estimate
the absolute non-linear parameter of the inspected object through
an operation of multiplying the calculated ratio of the relative
non-linear parameters by the absolute non-linear parameter of the
reference sample as exhibited in Equation 9 given below. As a
result, according to the exemplary embodiment of the present
disclosure, the estimated absolute non-linear parameter of the
inspected object may be acquired as the non-linear parameter of the
ultrasound signal.
.beta.=.beta..sub.0r.sub..beta. [Equation 9]
[0069] Where, .beta. represents the absolute non-linear parameter
of the inspected object, .beta..sub.0 represents the absolute
non-linear parameter value, and r.sub..beta. represent the ratio of
the relative non-linear parameter values.
[0070] The strength estimating unit 140 obtains a tensile curve by
using the linear and non-linear elastic coefficients and estimates
at least one of tensile strength and yield strength by using the
tensile curve.
[0071] That is, the strength estimating unit 140 substitutes the
linear elastic coefficient, the 2nd order non-linear elastic
coefficient, and the 3rd order non-linear elastic coefficient in
Equation 10 given below to obtain the tensile curve and contrary to
this, substitutes the linear elastic coefficient, the 2nd order
non-linear parameter, and the 3rd order non-linear parameter in
Equation 11 given below to obtain the tensile curve.
.sigma.=E.epsilon.-1/2F.epsilon..sup.2+1/6G.epsilon..sup.3+ . . .
[Equation 10]
[0072] Where, .sigma. represents stress and .epsilon. represents
deformation rate. Further, E represents the linear elastic
coefficient, F represents the 2nd order non-linear elastic
coefficient, and G represents the 3rd order non-linear elastic
coefficient.
.sigma.=E.epsilon.(1-1/2.beta..epsilon.+1/3.gamma..epsilon..sup.2+
. . . ) [Equation 11]
[0073] Where, .sigma. the represents stress and .epsilon.
represents the deformation rate. In addition, .beta. represents the
2nd order non-linear parameter and .gamma. represents the 3rd order
non-linear parameter.
[0074] The strength estimating unit 140 may estimate the tensile
strength from a maximum value of the tensile curve and estimate the
yield strength by applying 0.2% offset to the tensile curve as
illustrated in FIG. 4.
[0075] The degradation assessing unit 150 may assess a damage time
of the inspected object based on an accumulated non-linear
parameter calculated by accumulating a variation amount of the
non-linear parameter.
[0076] To this end, the signal processing unit 130 obtains the
non-linear parameter of the ultrasound signal received by the
ultrasound receiving unit 120 depending on the time and accumulates
the variation amount of the non-linear parameter to calculate the
accumulated non-linear parameter.
[0077] That is, the signal processing unit 130 substitutes an
initial non-linear parameter and the variation amount of the
non-linear parameter in Equation 12 given below to calculate the
accumulated non-linear parameter.
.beta..sub.c=.beta..sub.0+.SIGMA.|.DELTA..beta.| [Equation 12]
[0078] Where, .beta..sub.c represents the accumulated non-linear
parameter, .beta..sub.0 represents the initial non-linear
parameter, and .beta..sub..DELTA. represents the variation amount
of the non-linear parameter depending on the time. For reference,
when the material is heat-treated, .beta.c of Equation 12 may be
substituted even in Equation 11.
[0079] When the accumulated non-linear parameters .beta..sub.c are
the same as each other even though high-temperature degradation is
performed at different heat-treatment temperatures, the degradation
assessing unit 150 determines that the same damage is given, and as
a result, the degradation assessing unit 150 may determine a damage
degree of the material (inspected object) and assess the damage
time of the inspected object through the accumulated non-linear
parameters.
[0080] In the exemplary embodiment of the present disclosure, as
illustrated in FIG. 2, the non-linear parameter depending on a
heat-treatment time of the aluminum alloy is measured and as
illustrated in FIG. 3, as a result of an experiment that acquires
the accumulated non-linear parameters depending on the
heat-treatment time of the aluminum alloy, when the accumulated
non-linear parameters is the same, it may be determined that the
same damage is given.
[0081] As a result, the degradation assessing unit 150 may
determine the damage degree of the material (inspected object) and
assess the damage time of the inspected object based on the
accumulated non-linear parameters.
[0082] The control unit 160 may generally control operations of the
apparatus 100 for assessing degradation and estimating strength by
using ultrasound according to the exemplary embodiment of the
present disclosure, that is, the ultrasound transmitting unit 110,
the ultrasound receiving unit 120, the signal processing unit 130,
the strength estimating unit 140, the degradation assessing unit
150, and the like.
[0083] FIG. 5 is a flowchart illustrated for describing a method
for assessing degradation and estimating strength by using
ultrasound according to an exemplary embodiment of the present
disclosure. The method may be performed by the apparatus 100 for
assessing degradation and estimating strength of FIG. 1.
[0084] Referring to FIG. 5, in step 510, the apparatus for
assessing degradation and estimating strength makes the ultrasound
signal having a single frequency be incident in the inspected
object.
[0085] Next, in step 520, the apparatus for assessing degradation
and estimating strength receives the ultrasound signal penetrating
the inspected object or reflected on the inspected object.
[0086] Next, in step 530, the apparatus for assessing degradation
and estimating strength calculates the propagation speed through
the time interval of the received ultrasound signal.
[0087] Next, in step 540, the apparatus for assessing degradation
and estimating strength separates the received ultrasound signal
into the fundamental frequency component and the harmonic component
to calculate the non-linear parameter.
[0088] Next, in step 550, the apparatus for assessing degradation
and estimating strength measures the linear and non-linear elastic
coefficients by using the propagation speed and the non-linear
parameter.
[0089] In detail, referring to FIG. 6, in step 610, the apparatus
for assessing degradation and estimating strength may measure the
linear elastic coefficient based on the propagation speed.
Thereafter, in step 620, the apparatus for assessing degradation
and estimating strength may measure the 2nd order non-linear
elastic coefficient and the 3rd order non-linear elastic
coefficient by using the 2nd order non-linear parameter, the 3rd
order non-linear parameter, and the linear elastic coefficient.
[0090] As another exemplary embodiment, referring to FIG. 7, in
step 710, the apparatus for assessing degradation and estimating
strength may estimate the absolute non-linear parameter of the
inspected object by using the ratio of the relative non-linear
parameters of the reference sample and the inspected object and the
absolute non-linear parameter of the reference sample. Therefore,
in step 720, the apparatus for assessing degradation and estimating
strength may measure the linear and non-linear elastic coefficients
by using the propagation speed and the absolute non-linear
parameter.
[0091] Referring back to FIG. 5, in step 560, the apparatus for
assessing degradation and estimating strength acquires the tensile
curve by using the linear and non-linear elastic coefficients.
[0092] Next, in step 570, the apparatus for assessing degradation
and estimating strength estimates the tensile strength and/or the
yield strength by using the tensile curve.
[0093] FIG. 8 is a flowchart illustrated for describing a method
for assessing degradation and estimating strength by using
ultrasound according to another exemplary embodiment of the present
disclosure. The method may be performed by the apparatus 100 for
assessing degradation and estimating strength of FIG. 1.
[0094] Referring to FIG. 8, in step 810, the apparatus for
assessing degradation and estimating strength makes the ultrasound
signal having the single frequency be incident in the inspected
object.
[0095] Next, in step 820, the apparatus for assessing degradation
and estimating strength receives the ultrasound signal penetrating
the inspected object or reflected on the inspected object.
[0096] Next, in step 830, the apparatus for assessing degradation
and estimating strength calculates the propagation speed through
the time interval of the received ultrasound signal.
[0097] Next, in step 840, the apparatus for assessing degradation
and estimating strength separates the received ultrasound signal
into the fundamental frequency component and the harmonic component
to calculate the non-linear parameter.
[0098] Next, in step 850, the apparatus for assessing degradation
and estimating strength calculates the accumulated non-linear
parameters by accumulating the variation amount of the non-linear
parameter depending on the time.
[0099] Next, in step 860, the apparatus for assessing degradation
and estimating strength assesses the damage time of the inspected
object based on the accumulated non-linear parameters.
[0100] Although the exemplary embodiments of the present disclosure
have been described in detail with reference to the accompanying
drawings, the present disclosure is not limited thereto and may be
embodied in many different forms without departing from the
technical concept of the present disclosure. Therefore, the scope
of the present disclosure should not be limited to the exemplary
embodiment and should be defined by the appended claims and
equivalents to the appended claims.
[0101] Although the present disclosure has been described by the
limited exemplary embodiments and drawings, the present disclosure
is not limited to the exemplary embodiments and various
modifications and transformations can be made by those skilled in
the art from the disclosure. The protective scope of the present
disclosure should be construed based on the following claims, and
all the technical concepts in the equivalent scope thereof should
be construed as falling within the scope of the present
disclosure.
* * * * *